diff --git a/secondary/testing/gmock/BUILD.gn b/secondary/testing/gmock/BUILD.gn
index c7e109d2a..9184d623c 100644
--- a/secondary/testing/gmock/BUILD.gn
+++ b/secondary/testing/gmock/BUILD.gn
@@ -2,6 +2,13 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+# Chromium's GN configuration for gmock now lives at testing/gmock/BUILD.gn.
+#
+# This configuration is left in the tree because it is pulled by V8 and PDFium,
+# and will be removed as soon as the projects switch off of it.
+#
+# Details at http://crbug.com/630705 and http://crrev.com/2779193002
+
 config("gmock_config") {
   # Gmock headers need to be able to find themselves.
   include_dirs = [
diff --git a/secondary/testing/gtest/BUILD.gn b/secondary/testing/gtest/BUILD.gn
index 7eeceef55..aa24d7eb4 100644
--- a/secondary/testing/gtest/BUILD.gn
+++ b/secondary/testing/gtest/BUILD.gn
@@ -2,6 +2,13 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+# Chromium's GN configuration for gtest now lives at testing/gtest/BUILD.gn.
+#
+# This configuration is left in the tree because it is pulled by V8 and PDFium,
+# and will be removed as soon as the projects switch off of it.
+#
+# Details at http://crbug.com/630705 and http://crrev.com/2779193002
+
 import("//build_overrides/gtest.gni")
 if (is_ios) {
   import("//build/config/ios/ios_sdk.gni")